Multipole electric circuit breaker with common tripping means



March 2, 1965 N. R. BEAUDOIN 3,171,932

MULTIPOLE ELECTRIC CIRCUIT BREAKER WITH COMMON TRIPPING MEANS Filed May20, 1963 2 Sheets-Sheet 1 OFF TR/PPED INVENTOR.

Byflq WAN Hi UDO/N, 5A

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March 2, 1965 N. R. BEAUDOIN MULTIPOLEJ ELECTRIC CIRCUIT BREAKER WITHCOMMON TRIPPING MEANS 2 Sheets-Sheet 2 Filed May 20, 1965 INVENTOR.NORMAN RIB/E4 UDO/N, By W 7 ATTORNEY.

United States Patent M 3,171,932 MULTIPOLE ELECTRIC CIRiIUIT BREAKERWITH COMMON TRIPPING MEANS Norman R. Beaudoin, Southington, Conm,assignor to General Electric Company, a corporation of New York FiledMay 20, 1963, Ser. No. 281,593 3 Claims. (ill. 200116) My inventionrelates to multipole electric circuit breakers, and particularly tointerlocked tripping means for current responsively tripped circuitbreakers having individual overload tripping elements associated witheach pole of the breaker, ie. with each pair of cooperating contactmembers. This invention is an improvement upon that described andclaimed in application S.N. 268,738, filed March 28, 1963, by D. B.Powell and assigned to the same assignee as the present invention.

The invention is especially well adapted for use with small manuallyoperable, current responsively tripped air circuit breakers of thesingle pole type commonly mounted in multiple arrays for the control ofbranch lighting and power loads, such as in residential and commercialservice entrance load centers, industrial distribution panelboards andthe like. Such panelboard circuit breakers are commonly made up with oneor more single pole breakers in a single casing and may be utilizedseparately as single pole branch breakers or in ganged pairs as doublepole breakers. When two such circuit breakers are electrically connectedfor double pole use in a single branch circuit, it is desirable toensure that both breakers in any one circuit trip in response toactuation of the trip element of either of them. This is true whether ornot the manually operating elements of the two breakers are coupled forsimultaneous actuation.

As shown in Patent 2,779,881, Thomas, single pole circuit breakers ofthe foregoing type have been coupled for simultaneous tripping of twobreakers which are disposed in side-by-side relation. The interlockingelement there disclosed is positioned exteriorly of and between siderecessed circuit breaker casings. Ganged breakers of this design thusrequire special casings the expense of which increases the cost of fullline manufacture. Moreover, the lateral casing recess requires anindividual breaker design of appreciable thickness module.

In order to simplify and speed the installation of service entranceequipment and reduce cost there has been an increasing use of multipleassemblies consisting of several complete single pole circuit breakersmounted in a single integral casing. It is desirable that such breakersbe of a design to provide for either individual or ganged operation withminimum use of special parts. Also, the trend to increasing numbers ofbranch circuits to meet growing residential and commercial power loadshas led to panelboard circuit breaker designs of smaller physical size.Primarily it is desirable to decrease appreciably the thicknessdimension of such breakers to permit more circuits in a panelboard ofpredetermined length. While the thickness module of commerciallyavailable circuit break ers of the type shown in the Thomas patent iscommonly about one inch, it is now a growing practice to design for onehalf inch thickness. A circuit breaker of such narrow dimension requiresa mechanism of simplified and narrow design and leaves very little spacefor any lateral interconnection between breakers.

Accordingly it is a general object of my invention to provide improvedmeans for optionally interconnecting the separate operating mechanismsof several single pole electric circuit breakers with a minimum numberof special parts.

It is a more particular object of my invention to provide means interiorof the casing for interconnecting the operat- 3,171,932 Patented lVlar.2, 1965 ing mechanisms of a pair of circuit breakers disposed inend-to-end or tandem relation in integral or separate casings ofextremely narrow proportion relative to requisite mechanical strengthand electrical clearance.

It is a specific object of my invention to provide means interior of thecasing for interconnecting the trip elements of a pair of electriccircuit breakers assembled in end-toend relation in a single unitarycasing and having manually operable wedge type operatnig mechanismslaterally releasable upon current overload.

In carrying out my invention in one preferred embodiment, I providewithin a single narrow casing of suitable molded plastic insulatingmaterial, a pair of substantially identical single pole electric circuitbreakers disposed in essentially co-planar end-to-end or tandemrelation. Each circuit breaker includes a pair of separable contacts, amoveable current responsive trip member and manually operable wedgingmeans therebetween. Individual latch members responsive to the currentthrough the respective pairs of contacts normally restrain the tripmembers against movement but when released permit the trip membersagainst movement but when released permit the trip members to laterallyrelieve and release the wedge.

To ensure that overload tripping of any one such endto-end pair ofbreakers effects like tripping operation of the other, I provide asingle flat interlocking bar interiorly of the casing which ispositioned to be engaged and moved longitudinally by a part or" themanual operating mechanism of either breaker in its trip operation. Thedriving part of each operating mechanism is one which moves through adistinctive path in automatic trip operation only. The interlocking baris provided with portions disposed to engage and unlatch the currentresponsive trip element of either breaker which is itself not releasedby the overload current. Preferably the manual operating handles of thetwo breakers are also coupled together and the operating mechanisms areof the trip-free type. By this arrangement the manual handle of eitherbreaker which is separately tripped by o-vercurrent is held by the otherbreaker in its on position until the second breaker is tripped by theinterlock bar. Such handle interconnection ensures reliable operation ofthe trip interlock even with breaker mechanisms of the automatic resettype.

Further objects and advantages of my invention will be apparent to thoseskilled in the art from the following detailed specification taken inconjunction with the ac companying drawings in which:

FIG. 1 is a side elevational view of a pair of single pole electriccircuit breakers embodying my invention, the breakers being shown intheir open circuit position I with a side of the casing removed;

FlG. '2 is a side elevational view similar to FIG. 1 showing the samecircuit breakers in their circuit closing positions;

FIG. 3 is a side elevational view similar to FIGS. 1

' and 2 showing the same circuit breakers in their automatically trippedpositions but with the manual handles held against movement, i.e. thetrip free position; and

FIG. 4 is a fragmentary transverse cross sectional view of one of thecircuit breaker mechanism taken along the 1 line 44 of FIG. 2.

described and claimed in a co-pending patent application SN. 248,293filed on January 2, 1963, by Klein and Powell and assigned to the sameassignee as the instant application.

As illustrated in the drawings, my multipole circuit breaker consists oftwo individual single pole circuit breaker mechanisms mounted inend-t'o-end relation in a single narrow and elongated casing 10. In thedrawing one side of the casing has been removed to expose the operatingmechanism. In the lower central portion of the casing it) there arelocated a pair of line terminal clips 11 and 11a adapted to be disposedin clamping reiation on a pair of side-by-side flat busbars B. Through apivoted contact arm 12 of one circuit breaker 13 the line terminal clip11 is connected to a first load terminal 14 disposed at one end of thecasing 1UP and serving as a fixed switch contact member. Similarly theline terminal clip 11a, serving in this case as the fixed contact memberof the other circuit breaker 13a, is connected through a pivoted contactarm 12a of that circuit breaker to a second load terminal member 14a atthe opposite end of the casing It). The contact arms 12 and 12a are eachbiased to open circuit position by separate springs 4-0 and actuated toclosed position by individual manually operable, current responsivelytripped mechanisms of identical structure to like parts of which thesame reference numerals will be applied.

Each operating mechanism for manually and automatically moving theseparate circuit breaker contact arms 12 and 12:: between their opencircuit and closed circuit positions comprises a releasable trippingmember 15, shown as a fiat plate of insulating material looselypivotally mounted upon a pivot pin 16 and having at its edge adjacentthe contact arm 12 a cam surface 1'7. The cam surface 17 is formed intwo parts providing therebetween an apex point 17a with which a camfollower cooperates with an overcenter locking action to be more fullydescribed hereinafter. The releasable tripping member is normallyrestrained against tripping movement by means of a thermostatic latchmember 18 which is preferably of the type described and claimed in theforegoing application S.N. 248,293.

The lateral edge of the contact arm 12 adjacent the normally fixed camsurface 17 constitutes a cooperating cam surface 19 of essentiallylinear configuration and is disposed to converge toward the sam surface17 in the open circuit position of the parts as illustrated at FIG. 1.For manual closing and opening operation there is provided a movablewedging roller 20 rotatably mounted upon a pivot pin 21 at the free endof a swinging link 22. The link 22 is pivotally mounted eccentricallyupon a rotary handle member 23 carried by the fixed pivot 16. The handlemember 23 is provided with a radial arm 24 which extends through theupper end wall of the easing 10 to serve as a handle lever. The link 22is swingably mounted upon an internal arm of the handle 23 by means of apin 25. The upper portion of the handle member 23 is provided with anarcuate rim 26, one end of which serves as an abutment or shoulder toengage the releasable tripping member 15 when released and return it tolatched position. The two manual handles 24 are coupled together by alink 27 which is partially enclosed by an upper shroud portion We of theswitch housing. Both handles are biased to off or circuit openingposition by a spring 28 interposed between a housing abutment 10b and ashoulder 27a on the link 27. As described in the foregoing applicationS.N. 242,424, this operating mechanism is both trip free andautomatically resetting.

As previously stated, each of the individual circuit breaker mechanismsmounted in the single casing 10 includes a releasable trip member 15 ispivotally mounted upon the pivot 16 and normally restrained againsttripping movement by a current responsive latching member 18. In orderto couple the tripping members for simultaneous operation in the eventof overload release of only one of the trip member 15, I provide anelongated interlock bar 30 mounted for rectilinear sliding movement inthe casing 10 and having abutment portions 31, 31a disposed adjacent thetwo thermal latches 18 to engage and move these latches to releasingposition. The interlock bar is slidably mounted upon a fixed pin 30::and engages at its upper edge the spaced apart pivot pins 16. Adjacentthe circuit breaker 13a the interlock bar 3% is apertured at 32 and thecam roller pin 21 of the breaker 13a passes through the aperture. Oneedge surface 32a of aperture 32 is positioned to be engaged by the pin21 in its tripping movement when the associated trip member 15 isreleased by the thermal latch 18. A similar edge surface 32b of rod 30is positioned in like manner with respect to the roller 20 of circuitbreaker 13. Either pin 21 when released in trip opera tion to strike thesurface 3211 or 32b (directly or through the roller 20 as the case maybe) acts to drive the rod 34} to latch-releasing position (to the rightas shown in the drawing). The rod 30 is freely mounted, i.e. unbiased asto position, and is moved back to a normal position of non-interferencewith the latches by action of the roller pin 21 (on the breaker 13a) inresetting to its off or open position. In such resetting action the pin21 engages the edge surface 33 of aperture 32.

While it will be evident to those skilled in the art that any desiredtype of current responsive latch member may be utilized to restraintripping movement of the trip members 1d, I have shown a thermallyresponsive latch member in the form of a generally U-shaped bimetallicstrip loosely pivotally mounted at its bight and biased to latchingposition by means of a spring 35. As more fully described in theforegoing patent application SN. 248,293, the U-shaped bimetallic latchmember 18 is arranged when heated by a predetermined excessive currentto increase appreciably the divergence of its two legs and remove itslatching leg from engagement with the trip member 15. This isaccomplished by the free leg of the bimetal first engaging an abutmentportion 36 of the trip member 15 whereupon it acts as a prop so thatfurther thermal divergence causes unlatching movement of the latchingleg. Each bimetallic latch member 18 is rendered current responsive bypassing therethrough the current traversing the associated contact arm12 or 12a. For this purpose one leg of each bimetallic latch 18 isconnected by means of a flexible connector 37 to the associated contactarm 12 or 12a and the other leg of each bimetal is connected through aflexible connector 38 to the other terminal of its associated circuitbreaker.

At FIG. 4 I have shown a cross sectional view of one of the circuitbreakers of FIGS. 1, 2 and 3 to illustrate that, if desired, theprincipal operating parts may be made in dual or divided form with theinterlock bar 35 centrally located in the casing. As shown in that view,each trip member 15 is comprised of two identical plates one on eachside of the bar 30. Outside the two plates 15 and also mounted on thehandle pivot 16 is the divided or two-part handle member 23, the pairedparts being connected by a pin 42:: through the side-by-side handlelevers 24. The roller pin 21 is carried by a pair of spaced parallellinks 22, and the contact arm 12 is also made up of a pair of spacedapart and connected metal arms.

It will now be evident that in manual operation when the connectedhandle levers 24 are moved from the position of FIG. 1 to the positionof FIG. 2, the swingab le actuating links 22 are moved downwardly andthe wedging rollers 20 forced between the cam surfaces 17 and 19,respectively, of the releasable tripping members 15 and the respectivemovable contact arms 12 and 12a. The rollers 20 move overcenter on theapex points 17a of the normally fixed cam surfaces 17 and lock themovable contact arms 12 and 12a in closed circuit position against thebias of the contact springs 40, as shown at FIG. 2. In this position theforce of each spring 40 upon the associated contact arms 12 (or 12a) istransmitted through the wedging roller or cam follower 20 to thereleasable tripping member 15 by pressure against the normally fixed camsurface 17. This pressure from the contact bias spring serves, in thecircuit closing position of the mechanism, to bias the releasabletripping member 15 for counterclockwise movement (as shown in thedrawings) to a released or tripping position. Normally the releasabletrip members 15 are restrained against such tripping movement by thecurrent responsive latch members 18 so that in manual opening or closingoperation the trip member 15 is stationary. It will be evident thatmanual circuit opening movement for each of the breakers is the reverseof that described above for closing in that clockwise movement of thehandle levers 24 raises the swingable links 22 and removes the rollers20 from locked wedging position between the fixed cam surfaces 17 andthe contact arm surfaces 19.

Assuming now that both of the circuit breakers 13 and 13a are in theircircuit closing positions as shown at FIG. 2 and are being held manuallyin that position, the operation upon overload release will be asfollows. First let it be further supposed that only one pole of the dualcircuit breaker mechanism is affected by excessive overload current andthat only one of the bimetallic latch members 18 moves to unlatchingposition by the thermal action previously described. When that thermallatch is released, for example in the circuit breaker 13, the associatedtrip member 15 moves (counterclockwise as shown in the drawing) aboutits pivot 16 under the influence of the contact spring 40 acting throughthe contact arm 12 and the wedging roller 20. Such movement permits thecontact arm 12 to move to open circuit position and releases theswingable link 22 and roller 2t) for upward movement out of wedgingposition under the influence of the handle spring 28. The handles 24however are momentarily held in on position by the unreleased circuitbreaker mechanism 13a even if not manually held on as has been assumed.The release link 22 of circuit breaker 13 is therefore contained toswing counter-clockwise about its pivot 25 (i.e. to trip free position,as shown at FIG. 3), so that its roller pin 21 engages the edge surface32b of rod and drives that rod to the right. In moving to the right therod 30 (at its abutment 31a) engages the thermal latch 18 of circuitbreaker 13a and releases the trip member 15 of that breaker. When thesecond trip member 15 moves to trip-free position as shown at FIG. 3,both circuit breakers are open. If the handles 24 (assumed held on) arenow released their annular rims 26 engage the upper edges of the tripmembers 15 and return these members 15 to their normal latched positionsawaiting return of the latch members 18.

In resetting automatically to off position under the influence of handlespring 28 the link 22 of circuit breaker 13a is raised and moved in aclockwise direction from the position of FIG. 3 to that of FIG. l. Inthis movement the roller pin 21 of that breaker engages the edge 33 ofaperture 32 in the rod 30 and moves the rod 30 to the left to a position(FIGS. 1 and 2) of non-interference with the latches 18.

It will noW be evident to those skilled in the art that in the eventoverload current simultaneously affects both of the thermal latchmembers 18 but does so in different degree, due either to differentcurrent values or slightly unequal overload settings, the first circuitbreaker mechanism to trip will actuate the interlock bar 30 tomechanically force simultaneous tripping of the other breaker.

While I have illustrated the individual circuit breaker mechanismswithin the common casing 10 as having coupled manual operating handles24 (as shown at FIGS. 1, 2 and 3), it will of course be understood bythose skilled in the art that these handles may be independentlyoperable if desired. If the handles are independent, a thermallyreleased trip member 15 does not ordinarily move fully to its trip-freeposition before it is engaged and reset by the handle rim 26. The member15 moves only enough to release the roller 20, so that counterclockwiseswinging movement of the link 22 will be quite limited. Very closetolerance is then required to obtain adequate movement of rod 30.

It will also be understood by those skilled in the art that while myinvention has particular application to released wedge circuit breakermechanisms disposed in endto-end tandem relation, the particular type ofoperating mechanism is not significant except insofar as it must includesome manually operable part movable in automatic tripping operationthrough a path not transversed in manual operation. If an automaticreset mechanism is used, it is desirable to have it also trip-free inoperation and to couple the manual handles together to ensure reliableoperation of the trip interlock.

While I have illustrated only a preferred embodiment of my invention byway of illustration, many modifications will occur to those skilled inthe art, and I therefore wish to have it understood that I intend in theappended claims to cover all such modifications as fall Within the truespirit and scope of my invention.

I claim:

1. A pair of electric circuit breakers each including a pair ofseparable contacts and an individual actuating mechanism thereforehaving a manually operable handle biased to open circuit position, meansmounting said actuating mechanisms in end-to-end substantially coplanarrelation, each said mechanism including a wedging member movable througha predetermined path in manual operation and a releasable trip memberrestraining said wedging member against lateral movement, individuallatch means each responsive to excessive current through its associatedseparable contacts to release the respective wedge member for lateralcontact opening movement, a rectilinearly slidable interlocking memberhaving means engageable by each said wedging means in lateral movementand movable thereby to a latch-disengaging position, said interlockingmember having portions disposed to engage and move each said latch meansto releasing position, whereby current responsive release of either saidwedging member effects movement of said interlocking member to releasethe other said wedging member thereby to open both said circuit breakerssubstantially simultaneously.

2. A pair of electric circuit breakers each including a pair ofseparable contacts and a pivotally mounted movable contact arm biased toopen circuit position, individual circuit breaker actuating mechanismseach including a manually operable wedging member and a releasable tripmember, said trip members restraining said wedging members respectivelyagainst lateral movement, separate latch means responsive respectivelyto excessive current through the associated contact-s to release saidtrip members, common handle means biased to contact opening position andconnected to actuate said wedging members, said handle means biasingsaid trip member-s when released to latching position, and arectilinearly slidable interlocking member having means engageable byeach said wedging member upon lateral movement thereof to move saidinterlocking member to a latch-disengaging position, said interlockingmember having portions disposed to engage and move each said latch meansto releasing position, whereby current responsive unlatching of eithersaid trip member effects movement of said interlocking member to unlatchthe other said trip member thereby to open both said circuit breakerssubstantially simultaneously.

3. A multipole circuit breaker comprising a thin elongated flat casing,a pair of individual circuit breaker mechanisms mounted within saidcasing in end-to-end substantially co-planar relation and eachcomprising a pair of separable contacts including a flat blade-likemovable contact arm biased to open circuit position, each said circuitbreaker mechanism including also a m'ovably mounted fiat trip memberhaving an aperture therein and a cam surface on one edge thereof,manually operable wedge means movable between said contact arm and saidcam surface for manually opening and closing said contacts, saidmanually operable means including common handle means biased to offposition and arranged to engage and automatically return said tripmembers to latching position, separate latch means restraining said tripmembers against circuit-opening movement and responsive respectively toexcessive current through the associated Contact to release said tripmembers, said trip members when released laterally relieving said wedgemeans, and a flat elongated interlocking bar mounted for rectilinearslid- &

ing'movement within said casing and including means disposed for drivingengagement by either of sai d wedge means when laterallyrelieved, saidinterlocking barhaving portions disposed to engageand mechanicallyrelease each said latch means.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A.'GILHEAN Y, Primary Examiner.

1. A PAIR OF ELECTRIC CIRCUIT BREAKERS EACH INCLUDING A PAIR OF SEPARABLE CONTACTS AND AN INDIVIDUAL ACTUATING MECHANISM THEREFORE HAVING A MANUALLY OPERABLE HANDLE BIASED TO OPEN CIRCUIT POSITION, MEANS MOUNTING SAID ACTUATING MECHANISMS IN END-TO-END SUBSTANTIALLY COPLANAR RELATION, EACH SAID MECHANISM INCLUDING A WEDGING MEMBER MOVABLE THROUGH A PREDETERMINED PATH IN MANUAL OPERATION AND A RELEASABLE TRIP MEMBER RESTRAINING SAID WEDGING MEMBER AGAINST LATERAL MOVEMENT, INDIVIDUAL LATCH MEANS EACH RESPONSIVE TO EXCESSIVE CURRENT THROUGH ITS ASSOCIATED SEPARABLE CONTACTS TO RELEASE THE RESPECTIVE WEDGE MEMBER FOR LATERAL CONTACT OPENING MOVEMENT, A RECTILINEARLY SLIDABLE INTERLOCKING MEMBER HAVING MEANS ENGAGEABLE BY EACH SAID WEDGING MEANS IN LATERAL MOVEMENT AND MOVABLE THEREBY TO A LATCH-DISENGAGING POSITION, SAID INTERLOCKING MEMER HAVING PORTIONS DISPOSED TO ENGAGE AND MOVE EACH SAID LATCH MEANS TO RELEASING POSITION, WHEREBY CURRENT RESPONSIVE RELEASE OF EITHER SAID WEDGING MEMBER EFFECTS MOVEMENT OF SAID INTERLOCKING MEMBER TO RELEASE THE OTHER SAID WEDGING MEMBER THEREBY TO OPEN BOTH SAID CIRCUIT BREAKERS SUBSTANTIALLY SIMULTANEOUSLY. 